Owing to their tunable structures and strong emission, chiral metal–organic frameworks (CMOFs) incorporating rare-earth ions hold great promise for circularly polarized luminescence (CPL). Herein, enantiomeric rare-earth CMOFs are synthesized via the direct self-assembly of optically pure ligands (1,3-bis((S)- and (R)-1-carboxyethyl)-1H-imidazol-3-ium chlorides) with Tb³⁺ ions and shown to exhibit CPL with a dissymmetry factor (|g_lum|) of 0.016, which is attributed to efficient chirality transfer and the antenna effect. The introduction of a luminescent guest (MnCl₄²⁻) into the framework channels markedly enhances CPL and increases |g_lum| to 0.071. The results of control experiments and spectral analysis indicate that this enhancement arises from the synergy between host–guest energy transfer and chirality transfer. This work describes a modular strategy for constructing CPL-active rare-earth CMOFs and provides a general design principle for tuning their chiroptical properties through host–guest interactions.

In this study, we synthesized a visible-light-active titanium-oxo cluster (TOC), i.e., [(CH₃)₂NH₂]⁺₂·[Ti₄L₂(OⁱPr)₁₀]²⁻ (1), based on ellagic acid (H₄L). The molecular structure of 1 was determined using single-crystal X-ray diffraction, revealing a cyclodextrin-like tetramer formed by four Ti₄ clusters and dimethylamine cations. Owing to its effective ligand-to-metal charge transfer, 1 exhibited good visible-light absorption ability and photocurrent response, as confirmed by ultraviolet–visible (UV–vis) spectroscopy and photoelectric testing. Structurally, the large number of uncoordinated oxygen sites in 1 serve not only as assembly sites but also as active sites for NO₂ detection. Moreover, 1 exhibited high NO₂ response and excellent selectivity under visible-light irradiation at room temperature. This research provides the first exploration of TOCs in gas sensing applications, expanding their potential beyond traditional uses.